Centrifugal governor

ABSTRACT

The invention concerns a centrifugal governor comprising a rotatable driving member, a plurality of equi-angularly spaced apart flyweights which have driving connections with the said driving member so as to be rotated by the latter, at least portions of the flyweights being movable radially outwardly under centrifugal force, a rotatable and axially movable driven member having driving connections with the flyweights so as to be rotated thereby and so as to be moved axially thereby in a given axial direction when the flyweights move radially outwardly, the driving and driven members being coaxial, and means for urging the driven member in the opposite axial direction, all the said driving connections comprising relatively non-slidable parts which roll over each other during axial movement of the driven member in the said given axial direction.

United States P3181 [191 Johnson et al.

[ 1 Jan. 30, 1973 [54] CENTRIFUGAL GOVERNOR [75] Inventors: ChristopherLinley Johnson, l-lartshorne, near Burton-on-Trent; John Robert WilliamWhltmarsh; Kenneth Arnold Bastard, both of Derby, all of EnglandSecretary of State for Defence, London, England Filed: Nov. 13, 1970Appl. No.: 89,395

Assignee:

[30] Foreign Application Priority Data Nov. 17, 1969 Great Britain..56,l92/69 U.S. Cl. ..73/546, 73/551 Int. Cl. ..G05d 13/14 Field ofSearch ..73/534, 546, 550, 551, 535

References Cited UNITED STATES PATENTS 1,464,749 8/1923 Dahlstrand..73/546 X FOREIGN PATENTS OR APPLICATIONS 163,713 10/1905 Germany..73/551 408,694 111925 Germany ..73/535 Primary Examiner-James J. GillAttorney-Cushman, Darby 84 Cushman [57] ABSTRACT The invention concernsa centrifugal governor comprising a rotatable driving member, aplurality of equiangularly spaced apart flyweights which have drivingconnections with the said driving member so as to be rotated by thelatter, at least portions of the flyweights 'being movable radiallyoutwardly under centrifugal force, a rotatable and axially movabledriven member I having driving connections with the flyweights so as tobe rotated thereby and so as to be moved axially thereby in a givenaxial direction when the flyweights move radially outwardly, the drivingand driven members being coaxial, and means for urging the driven memberin the opposite axial direction, all the said driving connectionscomprising relatively non-slidable parts which roll over each otherduring axial movement of the driven member in the said given axialdirection.

4 Claims, 5 Drawing Figures PATENTEDJAIBOIHYS 3.713.344

SHEET 2 [IF 3 PATEN TEDJAI 3 0 I975 SHEET 3 [IF 3 mw M61 CENTRIFUGALGOVERNOR This invention concerns centrifugal governor, e.g., for use iscontrolling fuel flow through a fuel control system of a gas turbineengine.

According to the present invention, there is provided a centrifugalgovernor comprising a rotatable driving member,.a plurality ofequi-angularly spaced apart flyweights which have driving connectionswith the said driving member so as to be rotated by the latter, theflyweights, or portions thereof, being movable radially outwardly undercentrifugal force, a rotatable and axially movable driven member havingdriving connections with the flyweights so as to be rotated thereby andso as to be moved axially thereby in a given axial direction when theflyweights move radially outwardly, the driving and driven members beingcoaxial, and means for urging the driven member or a part positionedthereby, in the opposite axial direction, all the said drivingconnections comprising relatively nonslidable parts which roll over eachother during axial movement of the driven member in the said given axialdirection. I

Since the said parts of the driving connections are relativelynon-slidable and roll over each other as aforesaid, the hysteresis whichwould otherwise be apparent in the characteristic of the governor, as aresult of the friction between the flyweights and the driving and drivenmembers, is substantially avoided.

Each flyweight is preferably drivingly connected to both the driving anddriven members by flexible strips, each flexible strip extending overand being disposed between a curved surface of the flyweight and acooperating surface of the respective said member, radial movement ofeach flyweight under centrifugal force causing each curved surface toroll over the respective cooperating surface with the respectiveflexible strip interposed therebetween.

The said cooperating surfaces on the driving and driven members may beplanar and respectively normal to each other, the cooperating surfaceson the driven member being normal to the axis of the latter, the curvedsurfaces of the flyweights which roll over the cooperating surfaces onthe driven member having a circular cross-section, and the curvedsurfaces of the flyweights which roll over the cooperating surfaces onthe driving member having an involute cross-section whose base orgenerating circle is coincident with the surface of the circularcross-section.

The driving member is preferably a casing which is mountedconcentrically about the driven member and which is provided internallywiththe respective cooperating surfaces, means being provided forlimiting relative non-axial movement between the casing and drivenmember.

The driven member may have a plurality of equi-angularly spaced apartradial arms, one for each flyweight, the radially outermost portion ofeach radial arm being mounted within-a respective slot in the saidcasing to permit only limited radial and circumferential movement.

Each flyweight may be drivingly connected to the casing by two flexiblestrips which are respectively disposed on opposite sides of therespective radial arm.

The driven member may be an operating sleeve within which are mountedtwo concentric apertured sleeves the apertures in which control a liquidflow, the outer apertured sleeve being axially adjustable by theoperating sleeve to varythe degree of registration of the apertures inthe apertured sleeves and thus to control said flow.

The governor may be mounted within a housing adapted to be filled withsaid liquid, means being provided for compensating for changes in thespecific gravity of said liquid.

The invention is illustrated, merely by way of example, in theaccompanying drawings, in which:

FIG. 1 is a sectional view of a centrifugal governor according to thepresent invention,

FIG. 2 is a section taken on the line 2-2 of FIG. 1,

FIG. 3 is a diagrammatic section showing part of the structure of FIG. 1on a larger scale,

FIG. 4 is an elevation looking in the direction of arrow 4 of FIG. 1,and

FIG. 5 is a sectional view taken on the line 5-5 of FIG. 4.

The terms left and right as used in the description below, are to beunderstood to refer to directions as seen in the accompanying drawings Agas turbine engine fuel control system includes axially movable, outerand inner apertured sleeves 10, 11, having apertures l2, 13 respectivelywhich are relatively movable axially into increased and reducedcommunication with each other on relative axial movement of theapertured sleeves l0, 11. The apertured sleeves 10, 11 are mountedwithin a housing 14 which is filled with liquid fuel, the apertures 12,13 serving to meter a flow of this fuel within the housing 14.

The inner sleeve 11 is rotated (by means not shown), the outer aperturedsleeve being non-rotatable. The relative rotation between the aperturedsleeves 10, 11 reduces the risk of stiction between them, and thusrenders it easier to control the said fuel flow by axial adjustment ofthe outer apertured sleeve 10.

The apertured sleeve 10 is urged towards the right and towards contactwith an abutment 15 by means of a spring shown diagrammatically at 16.The spring 16 thus urges the apertured sleeve 10 is a direction tomaximize flow through the apertures 12, 13. The apertured sleeve 10, is,however, movable towards the left by means of a centrifugal governor 17which is mounted within the housing 14.

The centrifugal governor 17 comprises a rotatable, but axially fixed,casing 20 which constitutes a driving member of the centrifugal governorand which is formed integrally at its right hand end with a stub shaft21. The stub shaft 21 is provided with a gear wheel 22 by means of whichthe casing 20 is driven (by means not shown). Mounted within andadjacent to the left hand end of the casing 20 isan end plate 23 whichis secured within the casing 20, by means of a ring nut 24.

The casing 20 is mounted concentrically about a rotatable and axiallymovable operating sleeve 25 which constitutes the driven member of thecentrifugal governor 17. The operating sleeve 25 is provided with threeequi-angularly spaced apart radial arms 26. The radially outermostportion of each of the radial arms 26 is mounted for limited radial andcircumferential movement within a respective slot 27 (FIG, 2) in thecasing 20. Non-axial movement between the casing 20 and the operatingsleeve 25 is thus limited. Each of the radial arms 26 has a flyweight 30associated therewith.

Each of the flyweights 30 is provided with two heavy portions 31, andwith a curved surface 32 (FIG. 3) which merges into a planar surface 33.The curved surface 32 has a circular cross-section.

Each of the flyweights 30 is also provided with two curved surfaces 34each of which merges into a planar surface 35, the curved surfaces 34being respectively disposed on opposite sides of the curved surface 32.The curved surfaces 34 have an involute cross-section whose base orgenerating circle is coincident with the surface of the circular crosssection of the curved sur face 32. Alternatively, the curved surfaces 32could be formed to a curve other than a circle, in which case the curvedsurfaces 34 should be formed to an involute of said non-circular curve.

Each of the flyweights 30 is drivingly connected to the casing 20 by twoflexible spring steel strips 36 which are respectively disposed onopposite sides of the respective radial arm 26, while each flyweight 30is drivingly connected to the operating sleeve 25 by a single flexiblestrip 37.

Each of the flexible strips 36 is riveted, by a rivet 40, to the planarsurfaces 35, each flexible strip 36 extending over a curved surface 34and over a planar surface 41 provided internally of and out into thecasing 20. As will be seen from FIG. 2, there are a pair of parallel,planar surfaces 41 disposed on opposite sides of each slot 27, theplanar surfaces 41 facing radially inwardly and acting as cooperatingsurfaces over which the surfaces 34 may roll with the flexible strip 36interposed therebetween. Each of the flexible strips 36 is riveted tothe respective planar surface 41 by a rivet 38.

Each of the flexiblestrips 37, which is riveted by a rivet 42 to therespective planar surface 33, extends over the respective curved surface32 and is riveted to the radially outer part of a planar surface 43 ofthe respective radial arm 26 by a rivet 44. The planar surface 43 ofeach'radial arm 26 is normal both to the axis of the operating sleeve 25and to the planar surfaces 41. The curved surfaces 32 are adapted toroll over the planar surfaces 43 with the flexible strips 37 interposedtherebetween.

Each flyweight 30 is movable radially outwardly as a whole undercentrifugal force and is also rotatable by reason of radially outwardmovement of the heavy portions 31 under centrifugal force. Under suchcentrifugal force the curved surfaces 32, 34 will thus roll over thecooperating surfaces 41, 43 with the flexible strips 36, 37 interposedtherebetween and no hysteresisproducing sliding movement will occurbetween these parts.

Accordingly, in operation, when the casing 20 is rotated, movement isinitially imparted to each flyweight 30 by way of the flexible strips 36and is also imparted therefrom to the operating sleeve 25 by way of theflexible strips 37. Centrifugal forces will, however, cause the heavyportions 31 to move radially outwardly, and thiswill cause the surfaces32 to roll over theplanar surfaces 43, and will also cause the surfaces34 to roll over the surfaces 41. This in turn will cause the operatingsleeve 25 to move towards the left. The centrifugal forces, moreover,force the surfaces 34 towards the surfaces 41 and force the surfaces 32towards the surface 43, so that,- in addition to drive being transmittedthrough the flexible strips 36, 37, it is also transmitted frictionally.

Normally, there will, of course, be a clearance between the radial arms26 and the slots 27 in the easing 20. However, if distortion or breakageof a flexible strip 36, 37 occurs, a snubbing action will be effectedbetween the radial arms 26 and the casing 20 i to prevent relativeangular movemenL'Thus, for example, during start-up, the forces requiredto accelerate the flyweights 30 and the operating sleeve 25 may exceedthe load that can be carried by friction so that, but for this snubbingaction, the flexible strips 36, 37 would be badly distorted. Again thissnubbing action provides a fail-safe feature if the strips 36, 37 shouldbreak, since if this should occur the operating sleeve 25 will still belocated in approximately the correct position.

The operating sleeve 25 is arranged to transmit axial movement to anaxially movable sleeve 45 by way of a carbon thrust bearing 46, thesleeve 45 being axially slidable within the end plate 23. The sleeve 45has a dogged connection 50 to the apertured sleeve 10. The sleeves 10,45 are axially movable together but are prevented from rotation by aguide piece (not shown) on the apertured sleeve 10, the guide pieceengaging a part of the housing 14. Axial movement of the aperturedsleeve 10 towards the left reduces the degree of registration of theapertures 12, 13, whereby to reduce the fuel flow.

In the centrifugal governor shown in the drawings, the force produced bythe governor is independent of governor position and is dependent onlyupon the square of thespeed of rotation. However, as will beappreciated, it is possible to design the centrifugal governor of thepresent invention so as to provide other governor characteristics.

The flyweights 30 are immersed in fuel within the housing 14 and thusthe effect of centrifugal forces on them will depend upon the specificgravity of the fuel present. Each flyweight may therefore, if desired,be provided with a counterweight (not shown) made of a light materialsuch that the centrifugal forces acting upon it are also dependent uponthe specific gravity of the fuel present, but act in the oppositedirection to the centrifugal forces acting on the heavy portions 31.Thus the specific gravity of the fuel, and hence its temperature, wouldhave substantially no effect upon the operation of the governor.

We claim:

1. A centrifugal governor comprising: a rotatable driving member havingplanar surfaces thereon; a rotatable and axially movable driven membermounted coaxially with respect to said driving member and having planarsurfaces thereon, said planar surfaces of said driving member. beingnormal to the planar surfaces of said driven member and said planarsurfaces of said driven member being normal to the driven members axis;means for urging said driven member in a predetermined axial direction;and a plurality of equiangularly spaced apart flyweights, each of saidflyweights being drivingly connected to both said driving and drivenmembers by flexible strips, each flexible strip extending over and beingdisposed, between a curved surface of the flyweight and cooperating withone of the planar surfaces of said respective driving and drivenmembers, said flyweights being movable by certifugal force radiallyoutwardly and causing each curved surface to roll over the respectiveplanar surface with the respective flexible strip interposedtherebetween to thereby move said driven member axially against saidurging means, the curved surfaces of the flyweights which roll over saidplanar surfaces on said driven member having a circular cross sectionand the curved surfaces of said flyweights which roll over the planarsurfaces of said driving member having an involute cross section whosepitch circle is of the same radius as that of said circular crosssection.

2. A governor as claimed in claim 1 in which the driving member is acasing which is mounted concentrically about the driven member and whichis provided internally with its respective planar surfaces, means being

1. A centrifugal governor comprising: a rotatable driving member havingplanar surfaces thereon; a rotatable and axially movable driven membermounted coaxially with respect to said driving member and having planarsurfaces thereon, said planar surfaces of said driving member beingnormal to the planar surfaces of said driven member and said planarsurfaces of said driven member being normal to the driven member''saxis; means for urging said driven member in a predetermined axialdirection; and a plurality of equi-angularly spaced apart flyweights,each of said flyweights being drivingly connected to both said drivingand driven members by flexible strips, each flexible strip extendingover and being disposed between a curved surface of the flyweight andcooperating with one of the planar surfaces of said respective drivingand driven members, said flyweights being movable by certifugal forceradially outwardly and causing each curved surface to roll over therespective planar surface with the respective flexible strip interposedtherebetween to thereby move said driven member axially against saidurging means, the curved surfaces of the flyweights which roll over saidplanar surfaces on said driven member having a circular cross sectionand the curved surfaces of said flyweights which roll over the planarsurfaces of said driving member having an involute cross section whosepitch circle is of the same radius as that of said circular crosssection.
 1. A centrifugal governor comprising: a rotatable drivingmember having planar surfaces thereon; a rotatable and axially movabledriven member mounted coaxially with respect to said driving member andhaving planar surfaces thereon, said planar surfaces of said drivingmember being normal to the planar surfaces of said driven member andsaid planar surfaces of said driven member being normal to the drivenmember''s axis; means for urging said driven member in a predeterminedaxial direction; and a plurality of equi-angularly spaced apartflyweights, each of said flyweights being drivingly connected to bothsaid driving and driven members by flexible strips, each flexible stripextending over and being disposed between a curved surface of theflyweight and cooperating with one of the planar surfaces of saidrespective driving and driven members, said flyweights being movable bycertifugal force radially outwardly and causing each curved surface toroll over the respective planar surface with the respective flexiblestrip interposed therebetween to thereby move said driven member axiallyagainst said urging means, the curved surfaces of the flyweights whichroll over said planar surfaces on said driven member having a circularcross section and the curved surfaces of said flyweights which roll overthe planar surfaces of said driving member having an involute crosssection whose pitch circle is of the same radius as that of saidcircular cross section.
 2. A governor as claimed in claim 1 in which thedriving member is a casing which is mounted concentrically about thedriven member and which is provided internally with its respectiveplanar surfaces, means being provided for limiting relative non-axialmovement between the casing and driven member.
 3. A governor as claimedin claim 2 in which the driven member has a plurality of equi-angularlyspaced apart radial arms, one for each flyweight, the radially outermostportion of each radial arm being mounted within a respective slot in thesaid casing to permit only limited radial and circumferential movement.